Replies

1. 
   Jeff_Clarke_ | Jun 18, 2001 04:53am | #1

   *
   Jon - I made a wood frame and dropped a 2-speed whole-house fan (2000 CFM with integral louvers) into our attic access opening (about 27" square). The feed is a long piece of BX cable and I wired a smoke detector above it to a relay that shuts down the fan in case of a fire (need 4-wire to smoke/relay for signalling leg).

   It's a little inconvenient/risky to have to lift the fan up and over for access, but we don't go in the attic much in the summer. It's also a little loud in this location, but less vibration than I thought there would be. You need plenty of makup air - if you run it on high without enough windows open it will backdraft the chimney flue (sooty smell) and any appliances with flues. It's only useful here (NJ) in April, May and September - too hot otherwise. You could also consider a thermostatically-controlled attic exhaust fan - they top out at about 1100 CFM I think.

   Total cost was about $600 four years ago.

   Jeff

1. 
   Jon_Byrd | Jun 18, 2001 06:04am | #2

   *Thanks, I forgot to mention:- I live in Atlanta, very hot here.- I got one of those gable exhaust fans - sounds like a helicopter hovering over the house.- We have no central air and with the poor roof ventilation, it really cooks here.- Home Depot had a belt drive 32" fan only for $195. Was your fan belt drive? I would imagine it would be much quieter if so.- I don't have a chimney, but I did read on the box that a minimum infeed is required. I wonder if the opposite gable vent plus the louvered opening would be sufficient. I would probably run a switch to it as opposed to an automatic thermostat for that reason. That way we could open the windows and turn it on.I never thought of a hinged option, that sounds interesting. Thanks.Jon

1. 
   Ralph_Wicklund | Jun 18, 2001 06:36am | #3

   *I've had the opportunity to remove a number of whole house fans. One was mounted in a verticle position and shrouded with a large hood on the intake side over grillework and suction actuated louvers in the ceiling. Another was horizontal, directly over the suction activated louveres. Both of these were in excess of four feet in diameter. None of the whole house fans drew air from anyplace but the house. Drawing air from an opposite gable would defeat the purpose of the fan.Had a little aluminum one-piece "whole house fan" about 2 feet in diameter in my own house. Removed it and used the hole for return air when we installed A/C. It did move a little air but nowhere near what those big old fan blades moved in the older houses.Spoiled now, A/C RULES.

1. 
   Ted_LaRue_ | Jun 18, 2001 06:43am | #4

   *I've lived in a house with a direct drive whole-house fan and another house with a belt drive whole-house fan. I think the direct drive was a little quieter....less stuff vibrating. I wouldn't hesitate to buy a belt drive, though. You say you have a 3' by 3' ceiling access hole into the attic. If you mount the "whole house" fan so that it draws only through that opening, then it will pull air through the house and push it out the attic gable vents. Just make sure you open a few windows when you run it. You could create a back-draft on a gas water heater's vent if you don't have enough windows open. Even just three standard windows wide open should be adequate. You could mount the fan directly in the ceiling hole (as Jeff Clarke did). I built a box over the hole and mounted the fan vertically in a permanent frame where one side of the box would be. I hinged the box so that it could be lifted up away from the fan without the fan moving. To access the attic I need to raise only the box, which is much lighter than the fan. The sides of the box can be 1/4" plywood or even cheap paneling. The frame can be light 1x3 lumber.

1. 
   allaround_ | Jun 18, 2001 02:37pm | #5

   *If you're concerned about having to cut and frame a hole in the ceiling.....There are fans available that sit on top of the middle joist of three ceiling joists with a "duct" that goes down to the bottom of the joists. The shutter has a fixed leaf in the middle to accomodate the center joist. They should be stocked by W W Grainger, but are probably available elsewhere as well. Be sure to have enough attic venting - cut in some gable vents or more roof vents - otherwise you won't get good air flow.

2. 
   Jeff_Clarke_ | Jun 18, 2001 03:14pm | #6

   *Jon - In Hotlanta I would opt for attic venting rather than whole-house. When it gets up to 80 deg. + and over 60% RH A/C is the way to go. It's a comfort issue, most people aren't too uncomfortable at 75-80 deg. if the RH can be held below 50%. Once the humidity is high, however (as it is in southern coastal states), ventilation through the house won't help much.Cooling the attic by forced ventilation can help the A/C.Jeff

3. 
   Jon_Byrd | Jun 19, 2001 01:39am | #7

   *Thanks to all. I think I will most likely just do the ridge and soffit vents as that is the first place to start anyway. I'm not sure that any of the fan options will be pleasing from a sound level standpoint. And as mentioned, the humidity needs to be cut down which will only happen with an AC. Thanks again for the assistance.Jon

4. 
   Rob_Susz_ | Jun 19, 2001 05:22am | #8

   *JonI would not recommend the attic exhaust fan if you install A/C. The attic fan actually pulls a negative pressure on the attic. Since nearly every house built leaks to the attic, the fan actually pulls cool air out of the house and INCREASES the cooling load.I see this stuff with the IR camera and the micromanometer all the time.-Rob

5. 
   Jim_Hassberger | Jun 19, 2001 09:47pm | #9

   *Jon:I put in one of the HD whole house fans recently. Other than a bent shaft (HD replaced the part) no problems. But -- I did notice that in the fan instructions, they specifically point out it is intended for horizontal installation only. It will probably work fine vertically (for a while), but may void the warrenty.

2. 
   Jon_Byrd | Jun 19, 2001 09:47pm | #10

   *
   I would like to install a whole house fan, but my only option right now would be a gable mount. I have a scuttle hole
   entrance to the attic right in the center of the house which is maybe 3' x 3' and gable openings in each end of the roof. No
   ridge vent, no soffit vents, yet. I was thinking of constructing a louvered door for the scuttle hole with screen on the back
   side. I seem to remember having a whole house fan gable mounted as a child, but i could be wrong. Would this be effective
   at cooling the house in this location? Or do they need to be mounted right above the hole. I'm not as interested in a breeze
   through the house as cooling the overall temperature. Thanks in advance.

   Jon Byrd